Jafama (Java Fast Math) is a Java library aiming at providing faster versions
of java.lang.Math treatments, at the eventual cost of 1e-15ish accuracy errors
but still handling special cases properly (NaN, +-Infinity, ties, etc.).
It also provides additional features, such as angles normalization methods,
inverse hyperbolic trigonometry, etc.

Java implementation of JSON Web Token (JWT)

Maven archetypes for creating different types of JavaFX application.

Maven plugin to run JavaFX 11+ applications

A utility class which aids in generating Java source files.

The Java Data Objects 2 (JDO) API is a standard interface-based
Java model abstraction of persistence, developed as Java Specification
Request 243 under the auspices of the Java Community Process.

JDOM is a Java-oriented object model which models XML documents.
It provides a Java-centric means of generating and manipulating
XML documents. While JDOM inter-operates well with existing
standards such as the Simple API for XML (SAX) and the Document
Object Model (DOM), it is not an abstraction layer or
enhancement to those APIs. Rather, it provides a means of
reading and writing XML data.

Jersey is the open source JAX-RS (JSR 311)
production quality Reference Implementation
for building RESTful Web services.

A set of annotations used for code inspection support and code documentation.

Jettison is a collection of Java APIs (like STaX and DOM) which read
and write JSON. This allows nearly transparent enablement of JSON based
web services in services frameworks like CXF or XML serialization
frameworks like XStream.

An optimized Java interface to libffi.

JFreeChart is a free 100% Java chart library that makes it easy for
developers to display professional quality charts in their applications.

JHighlight is an embeddable pure Java syntax highlighting library that supports
Java, Groovy, C++, HTML, XHTML, XML and LZX languages and outputs to XHTML. It
also supports RIFE (http://rifers.org) templates tags and highlights them
clearly so that you can easily identify the difference between your RIFE markup
and the actual marked up source.

This project contains Java enums for common POSIX constants. It is
predominately used to make calls into jnr-posix far simpler.

Java Native Runtime Enhanced X-platform I/O

JNR-FFI is a Java library for loading native libraries without writing JNI code
by hand, or using tools such as SWIG.

jnr-netdb is a java interface to getservbyname(3), getservbyport(3).

It tries to use the native functions if possible, falling back to parsing
/etc/services directly, and finally to an inbuilt table for use in environments
where neither native code, nor filesystem access is possible.

jnr-posix is a lightweight cross-platform POSIX emulation layer for Java,
written in Java and is part of the JNR project (http://github.com/jnr).

Unix sockets for Java.

This is a pure-java port of asmjit (http://code.google.com/p/asmjit/).

JUnit is a popular regression testing framework for Java platform.

JWNL is a Java API for accessing the WordNet relational dictionary.
WordNet is widely used for developing NLP applications, and a Java
API such as JWNL will allow developers to more easily use Java for
building NLP applications.

This Java library can split German compound words into smaller parts.
This is especially useful for German words but it can work with all languages,
as long as a dictionary and a class extending AbstractWordSplitter is provided.
So far, only German is supported and a German dictionary is included in the JAR.
Even though it will work for some adjectives it works best for nouns.